node_modules/json5/lib/util.js

const unicode = require('../lib/unicode')

module.exports = {
    isSpaceSeparator (c) {
        return unicode.Space_Separator.test(c)
    },

    isIdStartChar (c) {
        return (
            (c >= 'a' && c <= 'z') ||
        (c >= 'A' && c <= 'Z') ||
        (c === '$') || (c === '_') ||
        unicode.ID_Start.test(c)
        )
    },

    isIdContinueChar (c) {
        return (
            (c >= 'a' && c <= 'z') ||
        (c >= 'A' && c <= 'Z') ||
        (c >= '0' && c <= '9') ||
        (c === '$') || (c === '_') ||
        (c === '\u200C') || (c === '\u200D') ||
        unicode.ID_Continue.test(c)
        )
    },

    isDigit (c) {
        return /[0-9]/.test(c)
    },

    isHexDigit (c) {
        return /[0-9A-Fa-f]/.test(c)
    },
}